A couple of weeks into the semester, I ask students to write down on a piece of paper something that they like about the class and something that they don't like about the class. Some people call it "Yeahs and Nays." Based on the responses, I can then go into class and address the "Nays" that show up most often. If it is something that I can and want to change, I'll make the change and explain that I made the change in response to student feedback. If it something that I cannot or will not change, (like the basic structure of TBL), then I can at least explain (once again) why the class is structured the way it is.
In any event, I think that giving students an opportunity to complain early in the semester can reduce the complaints at the end of the semester.